1. Field of the Invention
This invention relates to a filling paste structure and process of wafer level package, and more particularly to a structure and process by using the top side face down filling paste to make flatness of dice surface and without overflowing or recessing on the surface of dice, thereby improving filling paste performance and life cycle during reliability testing.
2. Description of the Prior Art
As a suitable semiconductor device for a high-pin-count package, a semiconductor device having a BGA (Ball Grid Array) structure has been developed. In this semiconductor device with a BGA structure, a semiconductor chip is mounted on a chip mount area of a main surface of a base substrate by using adhesive material and several bump electrodes are positioned in an array on the back side thereof that is opposite to said main surface of the base substrate.
The CSP has been conventionally formed by a method in which a semiconductor wafer is cut into semiconductor chips, then the semiconductor chips are mounted on a base substrate serving as a package base at predetermined positions and bonded thereto, and they are collectively sealed with a resin, thereafter the sealing resin and the base substrate are cut into pieces together at the parts between the semiconductor chips. In another conventional method, a semiconductor wafer (not being cut into semiconductor chips yet) is mounted on a base substrate and bonded thereto, then the semiconductor wafer and the base substrate are cut together, and the cut and divided semiconductor chips and package bases are sealed with a resin.
However, in the former conventional manufacturing method, a problem exists in that the method essentially includes a step of positioning and mounting the cut and divided semiconductor chips one by one on the base substrate. Like wise in the latter conventional manufacturing method, a problem exists in that the method essentially includes a step of sealing the cut and divided semiconductor chips and package bases one by one with a resin. Both conventional methods require a number of working processes equal to the number of semiconductor chips, which results in a disadvantage of low productivity.
Besides, at present, filling paste process of any type IC device package is adopted directly printing filling paste among the dice, shown as FIG. 1. The pluralities of dice 91 are formed on a glass base substrate 90. Silicone rubber 92 is formed on the glass base substrate 90 by using a printing method. In general, such filling paste technique causes an overflow filling paste on the surface of the dice in printing direction and a recess filling paste on the surface of the dice in non-printing direction, shown as FIG. 2A and FIG. 2B, respectively. The filling paste may cover the bonding pad of the die. That is to say, such filling paste process of prior art will suffer yield and reliability issues owing to poor uniformity of the filling paste on the surface of the dice.
Therefore, the present provides a new filling paste process of wafer level package to improve yield and reliability of the dice of wafer level package.